1. Field of the Invention
The present invention relates to a polymer alloy material and to process for production thereof. The present invention also relates to a powdered polymeric material useful for producing the polymer alloy material and to a process for production thereof.
2. Description of the Prior Art
Mechanical alloying was developed in 1968 by J. S. Benjamin and is described in "Dispersion Strengthened Superalloys by Mechanical Alloying", Metall. Trans, Vol. 1, pg. 2493 (1970), the contents of which are herein incorporated by reference. Initial efforts at mechanical alloying were aimed at producing an alloy combining oxide dispersion strengthening with gamma prime precipitation hardening in a nickel-based superalloy intended for gas turbine applications. Over time, the mechanical alloying process evolved from production of complex oxide dispersion strengthened (ODS) alloys to a process for producing composite metallic powders capable of yielding alloys with controlled, extremely fine microstructures. Accordingly, it is known that the mechanical alloying process may be used to produce metal alloys that are otherwise difficult or impossible to produce utilizing conventional melt techniques.
Generally, mechanical alloying comprises two steps. In the first step, the material to be alloyed is introduced into a high energy ball mill and is ground over a long period of time to produce an extremely fine powder by the mechanism of repeatedly fracturing and cold welding the fine powder particles. Each fine powder particle is comprised of a very uniform mixture of the various elements comprising the alloy. The second step in the process comprising consolidating the fine powder particles below the melting point of the material by using controlled amounts of pressure, time and temperature as described in P. S. Gilman et al. in "Mechanical Alloying", Ann. Rev. Mater. Sci., Vol. 13, pg. 279 (1983), the contents of which are hereby incorporated by reference.
Polymers are materials which have widespread applicability due to their relatively low density, low cost and their ability to be easily shaped for their intended purpose. Conventionally, it has been convenient to process polymeric materials to make them into useful articles by utilizing thermoforming techniques wherein the polymer is heated to a point where it will flow at a reasonable rate under applied stress. Examples of such known thermoforming techniques include extrusion, injection molding and calendering. Unfortunately, these techniques cannot be applied to many polymers having a high melting point since such polymers remain as solids up to the point of degradation (D. M. Bigg, Polymer Engineering and Science, 17 (9), pg. 691 (1977)). Additionally, many polymers are physically incompatible when melted and mixed together resulting in phase separation thereof to produce a nonhomogeneous material having nonuniform physical properties. Thus, attempts at alloying polymeric materials have generally been limited to production of polymeric alloys based on using chemical reactions, such as block and graft copolymerization and interpenetrating polymer network techniques as described by L. H. Sperling in "Interpenetrating Polymer Networks and Related Materials", Plenum Press (1981), the contents of which are hereby incorporated by reference.
It would be desirable to have an improved process for producing an alloyed polymeric material comprising at least one polymer which could be applied to a larger variety of polymers.